High-speed commercial inserting machines (hereinafter referred to as “inserters”) are well-known and are capable of generating thousands of mail pieces per hour. Typically inserters assemble mail pieces by sequentially feeding envelopes to an inserting station at which a “collation” is inserted into each envelope. As is understood by those who are skilled in the art, the term “collation” refers to one or more sheets of paper (unfolded and/or folded sheets) that are stacked and/or nested compactly together to facilitate insertion of the entire group of sheets at one time into the envelope.
In some cases, pre-printed window envelopes are employed, and the addressee information is carried on one of the sheets that is inserted in such a manner as to allow the addressee information to be visible through the envelope window. In these case, no printing on the envelopes is needed during or after assembly of the mail piece. In other applications, the addressee information and/or other information is printed on the envelope as part of the process of generating the mail piece. Conventionally, this is done downstream from the point of insertion at a print station that operates so as to compensate for potential variations in thickness of the mail piece. If the print station fails to completely compensate for thickness variations, then print quality may be adversely affected.
In some applications, it may be desired to print information both on the front face of the envelope and on the envelope flap. For example, addressee information may be printed on the front face and a return address may be printed on the flap. A conventional way of accomplishing this goal may be to provide separate print engines for respectively performing the front face and flap printing.